Blockchain system including a distributed network of a plurality of nodes and a method for achieving an agreement between the plurality of nodes executed by processors of the block chain system

A method for achieving an agreement among a plurality of nodes connected to a distributed network of a blockchain system, the method comprising:

• receiving a candidate block in one round of a plurality of rounds by one node among a plurality of nodes able to be promoted to producer nodes, wherein each of the producer nodes is capable of generating a block for a predetermined time period for each round;
• determining, by the one node, whether the received candidate block is a valid candidate block;
• determining, by the one node, whether the received candidate block determined as the valid candidate block is an unapproved block;
• and
• determining, by the one node, whether to vote for approval of the received candidate block determined as the unapproved block by determining whether the received candidate block determined as the unapproved block is a first received candidate block which is a candidate block first received by the one node within the one round.